t7527: use test_when_finished in 'case insensitive+preserving'

t7527: use test_when_finished in 'case insensitive+preserving'

Most tests in t7527-builtin-fsmonitor.sh that start a daemon, use the
helper function test_when_finished with stop_daemon_delete_repo.
Function stop_daemon_delete_repo explicitly stops the daemon.  Calling
it via test_when_finished is needed for tests that don't check daemon's
automatic shutdown logic [1] and it is needed to avoid daemons being
left running in case of breakage of the logic of automatic shutdown of
the daemon.

Unlike these tests, test 'case insensitive+preserving' added in [2] has
a call to function test_when_finished commented out.  It was commented
out in all versions of the patch [2] during development [3].  This seems
to not be intentional, because neither commit message in [2], nor the
comment above the test mention this line being commented out.  Compare
it, for example, to "# unicode_debug=true" which is explicitly described
by a documentation comment above it.

Uncomment test_when_finished for stop_daemon_delete_repo in test 'case
insensitive+preserving' to ensure that daemons are not left running in
cases when automatic shutdown logic of daemon itself is broken.

[1] See documentation in "fsmonitor--daemon.h" for details.
[2] caa9c37ec0 (t7527: test FSMonitor on case insensitive+preserving
    file system, 2022-05-26)
[3] See mailing list thread
    https://lore.kernel.org/git/41f8cbc2ae45cb86e299eb230ad3cb0319256c37.1653601644.git.gitgitgadget@gmail.com/T/#t

Signed-off-by: Andrei Rybak <rybak.a.v@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>